A technology using a laser light source as the light source of a projector has been proposed in recent years. A laser light source, as compared with an ultra-high pressure mercury lamp (UHP lamp) that has been used as the light source of a projector, has various advantages including excellent color reproducibility, quick start, and a long life. An illuminator using a laser light source can use a hologram element. A hologram element can diffract laser light to not only shape and enlarge the illumination area but also make the light amount distribution uniform in the illumination area at the same time. The use of a hologram element allows functions that have been assigned to a plurality of elements to be integrated into one element. The use of a hologram element thus allows the optical system to be configured with a smaller number of parts and hence the size and footprint thereof to be more easily reduced. In particular, a surface-relief hologram element, in which a relief structure is provided in the surface of the element, uses only the relief structure to convert the wavefront of light for image reproduction, allowing reduction in size of the optical system as compared with that using a lens or the like. For example, JP-A-2003-270585 has proposed a technology of a projector using a hologram element in its illumination optical system.